In the production of semiconductor devices, a thin film is formed by using a method such as sputtering, and a predetermined pattern is formed on the thin film with a resist by lithography. Based on this pattern as an etching resist, the underlying thin film is selectively removed by etching, followed by a step of removing the resist by ashing. Thereafter, a step of removing the remaining deposition by using a remover is required.
As removers for conventional semiconductor devices with aluminum wirings, various remover compositions have been proposed, and removers in which a fluorine-containing compound is used, and removers in which an amine represented by hydroxylamine is used, have been mainly used.
However, with increasing demands for higher-speed and more highly integrated semiconductor devices, the wirings are finer and the wiring width is narrower, so that it has been an essential requirement to prevent occurrence of wiring corrosion (etching) by a remover during cleaning.
JP-A-Hei-10-55993 discloses, as a cleaning agent which does not corrode metal film, a remover composition composed of a quaternary ammonium salt or an organic ammonium carboxylate, ammonium fluoride, a water-soluble organic solvent, and an inorganic acid or an organic acid. This remover composition is effective for use in conventional devices with wirings of a wide wiring width. However, this remover composition has a problem with use in devices with wirings of a narrow wiring width, because ammonium fluoride is highly corrosive to aluminum wirings.
Also, JP 2000-267302 A discloses a remover composition containing a combination of an organic acid and a surfactant (an organic sulfate, a sulfonate, a fatty acid salt, and the like), but this remover composition has low deposition-removing power. When the amount of the organic acid is increased to improve deposition eliminability, corrosion of aluminum wirings occurs, so that a sufficient effect is not obtained. Therefore, to date, no remover composition has been obtained which satisfies both of deposition eliminability and low corrosiveness to aluminum wirings, which are required for devices with wirings of a narrow wiring width.
On the other hand, when via holes which connect wirings are formed, there is also an increasing tendency that a large quantity of titanium-based deposition is adhered, due to narrower wiring width, during etching of the titanium or titanium nitride on the bottom of the via holes. Further, these titanium-based depositions are solidified in the subsequent ashing step, which makes the removal cleaning of deposition very difficult. Therefore, a sufficient removability is not obtained even when a fluorine-containing compound-based remover or an amine-based remover is used for the removing.
In view of the above problem, there are proposed a remover containing hydrogen peroxide, a quaternary ammonium salt and a hydrogen peroxide compound (JP 2002-202618 A), a remover which contains hydrogen peroxide, a quaternary ammonium salt and an anticorrosive and is used under alkaline conditions (JP 2003-5383 A), and the like. However, these removers require removal cleaning to be done under high-temperature conditions, and the removability of titanium-based deposition is still insufficient. Consequently, these removers have not solved the problem.
Further, in an attempt to clean by using an aqueous cleaning agent containing a combination of an organic acid and water or a combination of an organic acid, a water-soluble solvent and water, as described in JP-A-Hei-10-256210 and JP-A-Hei-11-316464, there arises problems such as deposition eliminability is decreased and the anticorrosiveness for aluminum wirings is deteriorated, as compared with the initial cleaning stage, as a continuous cleaning is proceeded. Therefore, practically, a continuous cleaning cannot be performed for a long period of time, and the remover, when used, needs to be replaced with a new one in a short period of time.
On the other hand, in a system of phosphoric acid and ammonium phosphate as described in JP 2000-232063 A, and a system of ammonium fluoride, an acid and an organic ammonium carboxylate as described in JP-A-Hei-10-55993, though a change in cleaning performance with continuous cleaning is small, deposition dissolution and anticorrosiveness for aluminum wirings, which are the basic properties, cannot be attained sufficiently at the same time from the initial stage of cleaning.
In addition, each of JP-A-Hei-9-279189 and JP 2001-26890 A discloses an aqueous cleaning agent used for cleaning semiconductors. However, both of the cleaning agents insufficiently satisfy deposition eliminability and anticorrosiveness for aluminum wirings at the same time.
Particularly, it is difficult to use these conventionally known aqueous removers in semiconductor substrates and semiconductor devices with wirings having a narrow wiring width of 180 nm or less, which is required for higher-speed and more highly integrated semiconductors in the future.
Also, when conventionally known aqueous removers are used in an open-topped cleaning vessel for a long period of time, or used in a circulation system, there is a problem that semiconductor substrates and the like are contaminated over time. In a practical situation, a remover is replaced with a new one in a short period of time to deal with this problem.